Go to settings > Pricing > Discounts/span>/span>/span>

Check to see if the discount is in use. If it is in use it will have a module selected here and not say "Not in use" /span>

If it says "Not In Use" go to Settings > Pricing > Pricing Modules /span>

Select the pricing Module Example: Default Pricing Module and then add the discount under Discounts and press save /span>

Once added Go back under discounts and it will show the module selected under "In use by modules" /span>

Go to the desired proposal and refresh the Pricing if it does not show up under discounts /span>